Refactor SrcLoc and SrcSpan

[ghc-hetmet.git] / compiler / utils / IOEnv.hs

diff --git a/compiler/utils/IOEnv.hs b/compiler/utils/IOEnv.hs
index ba98b08..1f1dd8f 100644 (file)
--- a/compiler/utils/IOEnv.hs
+++ b/compiler/utils/IOEnv.hs
@@ -3,6 +3,7 @@
 --
 -- The IO Monad with an environment
 --
+{-# LANGUAGE UndecidableInstances #-}
 
 module IOEnv (
         IOEnv, -- Instance of Monad
@@ -12,6 +13,7 @@ module IOEnv (
 
         -- Errors
         failM, failWithM,
+        IOEnvFailure(..),
 
         -- Getting at the environment
         getEnv, setEnv, updEnv,
@@ -20,14 +22,19 @@ module IOEnv (
         tryM, tryAllM, tryMostM, fixM,
 
         -- I/O operations
-        IORef, newMutVar, readMutVar, writeMutVar, updMutVar
+        IORef, newMutVar, readMutVar, writeMutVar, updMutVar,
+        atomicUpdMutVar, atomicUpdMutVar'
   ) where
 
-import Panic            ( try, tryUser, tryMost, Exception(..) )
+import Exception
+import Panic
 
-import Data.IORef       ( IORef, newIORef, readIORef, writeIORef, modifyIORef )
+import Data.IORef       ( IORef, newIORef, readIORef, writeIORef, modifyIORef,
+                          atomicModifyIORef )
+import Data.Typeable
 import System.IO.Unsafe ( unsafeInterleaveIO )
 import System.IO        ( fixIO )
+import Control.Monad
 import MonadUtils
 
 ----------------------------------------------------------------------
@@ -61,15 +68,21 @@ thenM (IOEnv m) f = IOEnv (\ env -> do { r <- m env ;
                                          unIOEnv (f r) env })
 
 thenM_ :: IOEnv env a -> IOEnv env b -> IOEnv env b
-thenM_ (IOEnv m) f = IOEnv (\ env -> do { m env ; unIOEnv f env })
+thenM_ (IOEnv m) f = IOEnv (\ env -> do { _ <- m env ; unIOEnv f env })
 
 failM :: IOEnv env a
-failM = IOEnv (\ _ -> ioError (userError "IOEnv failure"))
+failM = IOEnv (\ _ -> throwIO IOEnvFailure)
 
 failWithM :: String -> IOEnv env a
 failWithM s = IOEnv (\ _ -> ioError (userError s))
 
+data IOEnvFailure = IOEnvFailure
+    deriving Typeable
 
+instance Show IOEnvFailure where
+    show IOEnvFailure = "IOEnv failure"
+
+instance Exception IOEnvFailure
 
 ----------------------------------------------------------------------
 -- Fundmantal combinators specific to the monad
@@ -94,7 +107,7 @@ fixM f = IOEnv (\ env -> fixIO (\ r -> unIOEnv (f r) env))
 
 
 ---------------------------
-tryM :: IOEnv env r -> IOEnv env (Either Exception r)
+tryM :: IOEnv env r -> IOEnv env (Either IOEnvFailure r)
 -- Reflect UserError exceptions (only) into IOEnv monad
 -- Other exceptions are not caught; they are simply propagated as exns
 --
@@ -102,15 +115,19 @@ tryM :: IOEnv env r -> IOEnv env (Either Exception r)
 -- to UserErrors.  But, say, pattern-match failures in GHC itself should
 -- not be caught here, else they'll be reported as errors in the program
 -- begin compiled!
-tryM (IOEnv thing) = IOEnv (\ env -> tryUser (thing env))
+tryM (IOEnv thing) = IOEnv (\ env -> tryIOEnvFailure (thing env))
+
+tryIOEnvFailure :: IO a -> IO (Either IOEnvFailure a)
+tryIOEnvFailure = try
 
-tryAllM :: IOEnv env r -> IOEnv env (Either Exception r)
+-- XXX We shouldn't be catching everything, e.g. timeouts
+tryAllM :: IOEnv env r -> IOEnv env (Either SomeException r)
 -- Catch *all* exceptions
 -- This is used when running a Template-Haskell splice, when
 -- even a pattern-match failure is a programmer error
 tryAllM (IOEnv thing) = IOEnv (\ env -> try (thing env))
 
-tryMostM :: IOEnv env r -> IOEnv env (Either Exception r)
+tryMostM :: IOEnv env r -> IOEnv env (Either SomeException r)
 tryMostM (IOEnv thing) = IOEnv (\ env -> tryMost (thing env))
 
 ---------------------------
@@ -119,6 +136,16 @@ unsafeInterleaveM (IOEnv m) = IOEnv (\ env -> unsafeInterleaveIO (m env))
 
 
 ----------------------------------------------------------------------
+-- MonadPlus
+----------------------------------------------------------------------
+
+-- For use if the user has imported Control.Monad.Error from MTL
+-- Requires UndecidableInstances
+instance MonadPlus IO => MonadPlus (IOEnv env) where
+    mzero = IOEnv (const mzero)
+    m `mplus` n = IOEnv (\env -> unIOEnv m env `mplus` unIOEnv n env)
+
+----------------------------------------------------------------------
 -- Accessing input/output
 ----------------------------------------------------------------------
 
@@ -137,6 +164,17 @@ readMutVar var = liftIO (readIORef var)
 updMutVar :: IORef a -> (a -> a) -> IOEnv env ()
 updMutVar var upd = liftIO (modifyIORef var upd)
 
+-- | Atomically update the reference.  Does not force the evaluation of the
+-- new variable contents.  For strict update, use 'atomicUpdMutVar''.
+atomicUpdMutVar :: IORef a -> (a -> (a, b)) -> IOEnv env b
+atomicUpdMutVar var upd = liftIO (atomicModifyIORef var upd)
+
+-- | Strict variant of 'atomicUpdMutVar'.
+atomicUpdMutVar' :: IORef a -> (a -> (a, b)) -> IOEnv env b
+atomicUpdMutVar' var upd = do
+  r <- atomicUpdMutVar var upd
+  _ <- liftIO . evaluate =<< readMutVar var
+  return r
 
 ----------------------------------------------------------------------
 -- Accessing the environment
@@ -162,17 +200,17 @@ updEnv upd (IOEnv m) = IOEnv (\ env -> m (upd env))
 -- (for efficiency)
 ----------------------------------------------------------------------
 
-{-# -- SPECIALIZE mapM          :: (a -> IOEnv env b) -> [a] -> IOEnv env [b] #-}
-{-# -- SPECIALIZE mapM_         :: (a -> IOEnv env b) -> [a] -> IOEnv env () #-}
-{-# -- SPECIALIZE mapSndM       :: (b -> IOEnv env c) -> [(a,b)] -> IOEnv env [(a,c)] #-}
-{-# -- SPECIALIZE sequence      :: [IOEnv env a] -> IOEnv env [a] #-}
-{-# -- SPECIALIZE sequence_     :: [IOEnv env a] -> IOEnv env () #-}
-{-# -- SPECIALIZE foldlM        :: (a -> b -> IOEnv env a)  -> a -> [b] -> IOEnv env a #-}
-{-# -- SPECIALIZE foldrM        :: (b -> a -> IOEnv env a)  -> a -> [b] -> IOEnv env a #-}
-{-# -- SPECIALIZE mapAndUnzipM  :: (a -> IOEnv env (b,c))   -> [a] -> IOEnv env ([b],[c]) #-}
-{-# -- SPECIALIZE mapAndUnzip3M :: (a -> IOEnv env (b,c,d)) -> [a] -> IOEnv env ([b],[c],[d]) #-}
-{-# -- SPECIALIZE zipWithM      :: (a -> b -> IOEnv env c) -> [a] -> [b] -> IOEnv env [c] #-}
-{-# -- SPECIALIZE zipWithM_     :: (a -> b -> IOEnv env c) -> [a] -> [b] -> IOEnv env () #-}
-{-# -- SPECIALIZE anyM          :: (a -> IOEnv env Bool) -> [a] -> IOEnv env Bool #-}
-{-# -- SPECIALIZE when          :: Bool -> IOEnv env a -> IOEnv env () #-}
-{-# -- SPECIALIZE unless        :: Bool -> IOEnv env a -> IOEnv env () #-}
+-- {-# SPECIALIZE mapM          :: (a -> IOEnv env b) -> [a] -> IOEnv env [b] #-}
+-- {-# SPECIALIZE mapM_         :: (a -> IOEnv env b) -> [a] -> IOEnv env () #-}
+-- {-# SPECIALIZE mapSndM       :: (b -> IOEnv env c) -> [(a,b)] -> IOEnv env [(a,c)] #-}
+-- {-# SPECIALIZE sequence      :: [IOEnv env a] -> IOEnv env [a] #-}
+-- {-# SPECIALIZE sequence_     :: [IOEnv env a] -> IOEnv env () #-}
+-- {-# SPECIALIZE foldlM        :: (a -> b -> IOEnv env a)  -> a -> [b] -> IOEnv env a #-}
+-- {-# SPECIALIZE foldrM        :: (b -> a -> IOEnv env a)  -> a -> [b] -> IOEnv env a #-}
+-- {-# SPECIALIZE mapAndUnzipM  :: (a -> IOEnv env (b,c))   -> [a] -> IOEnv env ([b],[c]) #-}
+-- {-# SPECIALIZE mapAndUnzip3M :: (a -> IOEnv env (b,c,d)) -> [a] -> IOEnv env ([b],[c],[d]) #-}
+-- {-# SPECIALIZE zipWithM      :: (a -> b -> IOEnv env c) -> [a] -> [b] -> IOEnv env [c] #-}
+-- {-# SPECIALIZE zipWithM_     :: (a -> b -> IOEnv env c) -> [a] -> [b] -> IOEnv env () #-}
+-- {-# SPECIALIZE anyM          :: (a -> IOEnv env Bool) -> [a] -> IOEnv env Bool #-}
+-- {-# SPECIALIZE when          :: Bool -> IOEnv env a -> IOEnv env () #-}
+-- {-# SPECIALIZE unless        :: Bool -> IOEnv env a -> IOEnv env () #-}